Heating, ventilating, and air conditioning (HVAC) systems may use airside economizers to reduce or eliminate the need for mechanical cooling when relatively cooler outside air temperatures exist. Airside economizers may selectively draw in cooler air when outside air conditions are favorable and limit outside air intake when conditions are not favorable for cooling. As outside temperatures drop from unfavorable to favorable (e.g., higher to lower), controls used to start economizer mode operations are traditionally based on a fixed temperature threshold.